Suffix delay and the terminal and preterminal suffix effects.

Abstract

The effects of suffix delay on recall of terminal and preterminal list items was investigated in two experiments. A presentation rate of 0.4 s/item was used for list items, and suffix delay varied from 0.4 to 1.0 s. In the first experiment, suffix condition varied randomly throughout the experimental session; in the second experiment, all trials on a particular suffix condition were blocked together. Recall of the terminal item increased in a linear fashion with suffix delay, but there was no effect of suffix delay on preterminal items. The results are interpreted as supporting Penney's (1985) two-mechanisms account of the suffix effect.Resume Les effets de d£lai du suffixe sur le rappel d'une liste d'items terminaux et preterminaux ont 6t£ investigue's lors de deux experiences. Un taux de presentation de 0.4 s/item a 6t6 utilise pour une liste d'items et le delai du suffixe variait de 0.4 a 1.0 s. Dans la premiere experience, la condition du suffixe variait au hasard pendant toute la session expeiimentale; dans la deuxieme experience, tous les essais d'une condition de suffixe particuliere dtaient mis ensemble. Le rappel de l'item terminal augmentait de facon lindaire avec le d61ai du suffixe; il n'y avait cependant pas d'effet de delai du suffixe sur les items pr&erminaux. Les resultats vont dans le sens de 1'hypothese de Penney (1985) sur les deux mecanismes de l'effet du suffixe.The suffix effect is a well established phenomenon in short-term memory. The stimulus suffix is a verbal item appended to a short list of letters, words, or digits that is usually to be recalled immediately after presentation in the correct order. Typically, the subject is instructed that (a) the suffix serves to mark the end of the list, (b) the suffix is the same word on each trial and is compared to a tone or buzzer control, and (c) the suffix is not to be recalled. When both list and suffix are presented auditorily, the suffix has a large detrimental effect on recall of the last few list items with the greatest effect usually observed for the last memory item. Penney (1985) proposed two mechanisms underlying the suffix effect: a terminal suffix effect due to the loss of finality of the terminal

Two-component theory of the suffix effect: Contrary evidence

“…With the data averaged across the last four positions, mean probability of recall was higher in the no-suffix condition (.63) In short, this experiment showed that delaying a hundred suffix attenuated its effect only slightly and, more important, that such attenuation as did occur was localized at the preterminal positions. This finding is thus entirely contrary to the assumption that the effect of suffix delay is restricted to the terminal position (e.g., Penney & Godsell, 1993). Moreover, this finding undermines the core assumption of the two-component theory (e.g., ; see also Nairne, 1990;Penney, 1989)-namely, that delaying a suffix, regardless of its conceptual (semantic) relationship to the list items, attenuates the effect of timedependent, structural overwriting and diminishes the terminal suffix effect.…”

“…Figure 4 shows the serial recall function for each suffix condition. Contrary to previous findings (e.g., Crowder, 1971;Frankish & Turner, 1984;Penney & Godsell, 1993), delaying the suffix failed to mitigate the terminal suffix effect. The relevant findings are as follows.…”

“…Previous research has shown that delaying the suffix serves to reduce the suffix effect-most notably (Bloom & Watkins, 1999;Crowder, 1969Crowder, , 1971Frankish & Turner, 1984), and sometimes exclusively (Penney & Godsell, 1993), at the terminal position. This finding has been interpreted in terms of the overwriting of time-dependent structural information (e.g., ; see also Nairne, 1990;Penney, 1989) and, therefore, as consistent with the two-component theory (e.g., Penney & Godsell, 1993). The results of Experiments 1 and 3 raise the intriguing possibility that this finding may not hold over all conditions.…”

“…258-259). Thus, the conceptual (semantic) relationship between the suffix and the list items is assumed neither to influence the terminal suffix effect nor to modulate the effect of suffix delay at the terminal position (e.g., Nairne, 1990;Penney & Godsell, 1993). And suffix effects obtained solely with static visual presentation either are predicted not to occur (e.g., or are not addressed (e.g., Nairne, 1990;Penney, 1985, p. 246).…”

“…Thus, participant strategy has been invoked to account for the finding that rate of item presentation affects the preterminal, but not the terminal, component of the suffix effect (Balota & Engle, 1981), whereas structural factors have been invoked to account for the finding that the delay between the last list item and the suffix affects only the terminal component of the suffix effect (Penney & Godsell, 1993), and both strategic and structural factors have been invoked to account for the finding that the acoustic length of the suffix has opposite effects on the preterminal and terminal components of the suffix effect (Baddeley & Hull, 1979).…”